[Linux-users] reverse dns

[vu pham]

On Tue, 2007-08-28 at 10:27 -0700, Bill Campbell wrote:
> On Mon, Aug 27, 2007, vu pham wrote:
> >When I run "w" on a server to show who are currently on the system, the
> >output also shows the dns names of the remote systems via the column
> >FROM. But I notice that all the systems which are under  the local dns
> >are displayed by their dns names, and all the others are displayed by ip
> >addresses.
> >
> >I tried nslookup/ptr on the server and it can resolve the name of all
> >the remote systems just fine. Don't know why they are displayed by just
> >the ip addresses.
> >
> >Any advice ?
> 
> dig -x ipaddress
> 

Thanks, Bill, but what am I supposed to look for ? dig -x also returns
the same name of the remote host which  nslookup returns. I mean this
particular ip has approprite PTR record, but why the "who" shows it by
ip address ?

All the internal PCs are displayed by name, and all the external systems
are displayed by ip so I think the firewall may block some kinds of
packets, but the reserved dns resolution works just fine on the server.

Vu